A variety of methods and devices for producing cooled gases are known at present.
According to one of such methods, volume oscillations are established in a gas stream so that the latter is split into two flows, a reduced pressure and temperature flow used for cold generation, and an elevated pressure and temperature flow used for heat generation (cf., e.g., USSR Author's Certificate No. 113,268, Cl. F 25 B 9/02, published 1989).
Known in the art presently is also use for gas cooling of Hartmann-Siringer acoustic generators, wherein the acoustical resonator gets heated to high temperatures due to formation of standing waves, though in this case the withdrawn gas is somewhat cooled (cf. "Effect of cooling in undulatory adiabatic gas expansion" by A. M. Arkharov et al., Proceedings of the USSR Academy of Sciences, Power and Transport, 1981, No. 2 (in Russian).
Both of the methods mentioned above are disadvantageous because of low efficiency of gas cooling and because of producing heat alongside with cold, which is useless and even harmful as far as refrigerating engineering is concerned.
The disadvantage mentioned above is also inherent in the most extensively used heretofore Ranque-Hilsh gas energy dividers based on the use of the so-called vortex tubes, wherein gas is subjected to swirling and acceleration, followed by its being discharged (exhausted) into the expansion chamber in which gas is divided into a cooled and a preheated stream (cf., e.g., U.S. Pat. No. 1,952,281, 1934, and also "The vortex effect and its engineering uses" by A. P. Merkulov, Moscow Mashinostroenie PH, 1969 (in Russian).
Apart from the disadvantage mentioned above, vortex tubes suffer from a reduced cooling effect in response to a higher gas intake pressure.
The most similar to the present invention as to its technical essence is the vortex cooler, comprising a scroll with a gradually tapered spiral duct, as well as a cold gas exit nozzle and an expansion chamber, each being situated on one side of the scroll, the expansion chamber has a throttle at one of its ends, the throttle appearing as a blank cover so fitted as to leave a gap for hot gas to escape (cf., e.g., U.S. Pat. No. 3,775,988 published 1973).
The device discussed above carries into effect the following gas cooling process. A stream of a cooled gas is pressure-admitted to the scroll through an inlet nozzle. While passing along the gradually tapered spiral duct of the scroll the gas stream gets swirled and accelerated to a supersonic velocity, whereupon it is discharged from the scroll into the expansion chamber which is shaped as a taper or cylindrical tube. While passing along a helical pathway over the chamber walls the gas stream reaches the blank cover, after which part of the stream is reflected from the blank cover and returns backward along the axial tube portion to be discharged through a cold gas exit nozzle (said part of the gas stream being hereinafter referred to as axial part, while the other part of the gas stream (that is, the peripheral one)) is discharged through exit ports provided at the place where the blank cover is held to the expansion chamber.
Throttling of the peripheral gas stream portion at the outlet thereof, according to the known method and device results in the onset of standing waves causing heating of said stream part, with the resultant elevation of the temperature in the axial part of the stream, which affects adversely the effectiveness of the cold generation process.